Modelling the energy performance of a farm-scale cellulose to ethanol process with on-site cellulase production and anaerobic digestion

A farm-scale process for converting wheat straw to ethanol was modelled to assess its energy performance. The process incorporates the on-site production of crude unprocessed liquid cellulase produced via solid-state fermentation, and the anaerobic digestion of process residues to supply heat and electricity. Results include energy yield ratios from 6 to 9, reductions of 80–90 % in the energy required to produce and transport the cellulase compared to commercial preparations, and a net surplus of on-site heat and electricity. From these improvements in process efficiency, environmental benefits follow.